Implement BYOB reader for WebTransport streams.

This CL implements BYOB reader for WebTransport streams. BYOB reader for
datagram will be implemented in a separate CL.

Bug: 1259886
Change-Id: Iebb980f9c6da3cff331c837d48f489650adf3a26
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3799089


Commit-Queue: Adam Rice <ricea@chromium.org>
Reviewed-by: Adam Rice <ricea@chromium.org>
Auto-Submit: Jianjun Zhu <jianjun.zhu@intel.com>
Reviewed-by: Nidhi Jaju <nidhijaju@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1045022}